A patent was purchased on 1/1/2016 for 150,000 with 15 years useful life .On 1/1/2017 the company paid legal defense fees of 89,000.on 1/1/2018 the management decided to impair the patent .they expected the future net cash flow 70,000 and fair value 108,000 required calculate the amortization expense for the years: 2016,2017,2018,2019 7